feat(settings): protect model provider deletion and cascade credential updates

- Block deletion of a model provider when it is referenced by any agent,
  returning an error that lists the agent names so the user knows what to unlink first
- When a provider's api_url or api_key is updated, automatically propagate
  the new credentials to all dependent agents: updates env_json in the database
  and patches on-disk config files (Claude Code settings.json, Gemini settings.json,
  Codex auth.json + config.toml, OpenCode auth.json) using the same field names
  and structure as the agent settings UI
- Fix error message display in provider dialogs for both Tauri and web transports,
  which throw plain objects rather than Error instances

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/settings/add-model-provider-dialog.tsx

@@ -89,8 +89,14 @@ export function AddModelProviderDialog({
       toast.success(t("createSuccess"))
       handleOpenChange(false)
       onProviderAdded()
-    } catch (err) {
-      const msg = err instanceof Error ? err.message : String(err)
+    } catch (err: unknown) {
+      const raw = err as Record<string, unknown>
+      const msg =
+        typeof raw?.message === "string"
+          ? raw.message
+          : err instanceof Error
+            ? err.message
+            : String(err)
       setError(msg)
     } finally {
       setLoading(false)

src/components/settings/edit-model-provider-dialog.tsx

@@ -97,8 +97,14 @@ export function EditModelProviderDialog({
       toast.success(t("editSuccess"))
       handleOpenChange(false)
       onProviderUpdated()
-    } catch (err) {
-      const msg = err instanceof Error ? err.message : String(err)
+    } catch (err: unknown) {
+      const raw = err as Record<string, unknown>
+      const msg =
+        typeof raw?.message === "string"
+          ? raw.message
+          : err instanceof Error
+            ? err.message
+            : String(err)
       setError(msg)
     } finally {
       setLoading(false)

src/components/settings/model-provider-settings.tsx

@@ -72,9 +72,21 @@ export function ModelProviderSettings() {
       toast.success(t("deleteSuccess"))
       setDeleteTarget(null)
       await loadProviders()
-    } catch (err) {
-      const msg = err instanceof Error ? err.message : String(err)
-      toast.error(msg)
+    } catch (err: unknown) {
+      const raw = err as Record<string, unknown>
+      const msg =
+        typeof raw?.message === "string"
+          ? raw.message
+          : err instanceof Error
+            ? err.message
+            : String(err)
+      const prefix = "PROVIDER_IN_USE:"
+      if (msg.includes(prefix)) {
+        const agentNames = msg.substring(msg.indexOf(prefix) + prefix.length)
+        toast.error(t("deleteBlockedByAgent", { agents: agentNames }))
+      } else {
+        toast.error(msg)
+      }
     }
   }, [deleteTarget, loadProviders, t])
 

src/i18n/messages/ar.json

@@ -1849,6 +1849,7 @@
     "deleteSuccess": "تم حذف المزود.",
     "deleteConfirmTitle": "حذف المزود",
     "deleteConfirmMessage": "سيتم حذف المزود \"{name}\" نهائياً. هل أنت متأكد؟",
+    "deleteBlockedByAgent": "{agents} يستخدم هذا المزود. يرجى إلغاء الربط قبل الحذف.",
     "cancel": "إلغاء",
     "delete": "حذف",
     "create": "إنشاء",

src/i18n/messages/de.json

@@ -1849,6 +1849,7 @@
     "deleteSuccess": "Anbieter gelöscht.",
     "deleteConfirmTitle": "Anbieter löschen",
     "deleteConfirmMessage": "Der Anbieter \"{name}\" wird dauerhaft gelöscht. Sind Sie sicher?",
+    "deleteBlockedByAgent": "{agents} verwendet diesen Anbieter. Bitte trennen Sie die Verbindung vor dem Löschen.",
     "cancel": "Abbrechen",
     "delete": "Löschen",
     "create": "Erstellen",

src/i18n/messages/en.json

@@ -1849,6 +1849,7 @@
     "deleteSuccess": "Provider deleted.",
     "deleteConfirmTitle": "Delete Provider",
     "deleteConfirmMessage": "This will permanently delete the provider \"{name}\". Are you sure?",
+    "deleteBlockedByAgent": "{agents} is currently using this provider. Please unlink before deleting.",
     "cancel": "Cancel",
     "delete": "Delete",
     "create": "Create",

src/i18n/messages/es.json

@@ -1849,6 +1849,7 @@
     "deleteSuccess": "Proveedor eliminado.",
     "deleteConfirmTitle": "Eliminar Proveedor",
     "deleteConfirmMessage": "Esto eliminará permanentemente el proveedor \"{name}\". ¿Está seguro?",
+    "deleteBlockedByAgent": "{agents} está usando este proveedor. Desvincúlelo antes de eliminarlo.",
     "cancel": "Cancelar",
     "delete": "Eliminar",
     "create": "Crear",

src/i18n/messages/fr.json

@@ -1849,6 +1849,7 @@
     "deleteSuccess": "Fournisseur supprimé.",
     "deleteConfirmTitle": "Supprimer le Fournisseur",
     "deleteConfirmMessage": "Le fournisseur \"{name}\" sera définitivement supprimé. Êtes-vous sûr ?",
+    "deleteBlockedByAgent": "{agents} utilise ce fournisseur. Veuillez le dissocier avant de supprimer.",
     "cancel": "Annuler",
     "delete": "Supprimer",
     "create": "Créer",

src/i18n/messages/ja.json

@@ -1849,6 +1849,7 @@
     "deleteSuccess": "プロバイダーを削除しました。",
     "deleteConfirmTitle": "プロバイダーを削除",
     "deleteConfirmMessage": "プロバイダー「{name}」を完全に削除しますか？",
+    "deleteBlockedByAgent": "{agents} がこのプロバイダーを使用中です。削除する前にリンクを解除してください。",
     "cancel": "キャンセル",
     "delete": "削除",
     "create": "作成",

src/i18n/messages/ko.json

@@ -1849,6 +1849,7 @@
     "deleteSuccess": "제공업체가 삭제되었습니다.",
     "deleteConfirmTitle": "제공업체 삭제",
     "deleteConfirmMessage": "제공업체 \"{name}\"을(를) 영구적으로 삭제하시겠습니까?",
+    "deleteBlockedByAgent": "{agents}이(가) 이 공급자를 사용 중입니다. 삭제하기 전에 연결을 해제해 주세요.",
     "cancel": "취소",
     "delete": "삭제",
     "create": "생성",

src/i18n/messages/pt.json

@@ -1849,6 +1849,7 @@
     "deleteSuccess": "Provedor excluído.",
     "deleteConfirmTitle": "Excluir Provedor",
     "deleteConfirmMessage": "O provedor \"{name}\" será excluído permanentemente. Tem certeza?",
+    "deleteBlockedByAgent": "{agents} está usando este provedor. Desvincule-o antes de excluir.",
     "cancel": "Cancelar",
     "delete": "Excluir",
     "create": "Criar",

src/i18n/messages/zh-CN.json

@@ -1849,6 +1849,7 @@
     "deleteSuccess": "供应商已删除。",
     "deleteConfirmTitle": "删除供应商",
     "deleteConfirmMessage": "确定要永久删除供应商「{name}」吗？",
+    "deleteBlockedByAgent": "{agents} 正在使用该配置，请先解除关联后再删除。",
     "cancel": "取消",
     "delete": "删除",
     "create": "创建",

src/i18n/messages/zh-TW.json

@@ -1849,6 +1849,7 @@
     "deleteSuccess": "供應商已刪除。",
     "deleteConfirmTitle": "刪除供應商",
     "deleteConfirmMessage": "確定要永久刪除供應商「{name}」嗎？",
+    "deleteBlockedByAgent": "{agents} 正在使用此設定，請先解除關聯後再刪除。",
     "cancel": "取消",
     "delete": "刪除",
     "create": "建立",